1. Field of the Invention
This invention relates generally to spin valve transistors (SVT) for magnetic read heads and methods of making the same.
2. Description of the Related Art
A spin-valve transistor (SVT) is a hybrid device in which ferromagnetic and semiconductor materials have been functionally integrated. The SVT is based on spin-dependent transport but, unlike other magnetoresistive devices, it relies on the spin-transport of a portion of transmitted electrons which are energetic xe2x80x9chotxe2x80x9d electrons. Similar to a transistor, a conventional SVT has three terminals which include a base, emitter, and collector. In the SVT, the collector is made from semiconductor materials (such as silicon) but the other materials are magnetic and contain an anti-ferromagnet. In principle, a wide range of semiconductor and magnetic materials may be utilized. At the interface between the metal base and the semiconductor, an energy barrier (or xe2x80x9cSchottkyxe2x80x9d barrier) is formed. To obtain a high-quality Schottky barrier which has a good rectifying behavior, thin layers of platinum and gold, for example, are incorporated at the emitter and collector side, respectively. These layers also separate the magnetic layers from the direct contact with silicon.
As described, several layers of materials form an SVT and GMR sensor. However, it has become increasingly important to reduce the profile of a read sensor such that higher recording densities can be achieved in magnetic media. Unfortunately, a simple reduction of materials or material thickness within the sensor adversely affects the sensor properties.
Accordingly, what is needed is a read sensor that has a thinner profile at the media interface so that higher recording densities can be achieved.
A spin valve transistor (SVT) for a magnetic head and a method of making the same are described. A slider of a disk drive is formed of a semiconductor material, such as silicon. The sensor has a free layer formed over the semiconductor material and a magnetic pinned layer formed over a portion of the free layer. The free layer has an edge that is substantially flush with an air bearing surface (ABS) of the magnetic head, whereas the magnetic pinned layer has an edge that is recessed away from the ABS. Advantageously, since the free layer serves as a flux guiding structure for the sensor, the sensor has a thinner profile at the ABS to accommodate higher recording densities.